#include<stdlib.h>
#include<time.h>
#include<string.h>
#include"des.h"
//构造函数
Des::Des(){
	bm32[31]=1;
	for(int i=30;i>=0;i--){
		bm32[i]=bm32[i+1]<<1;
	}
	bm64[63]=1;
	for(int i=62;i>=0;i--){
		bm64[i]=bm64[i+1]<<1;
	}
}

//置换选择表
const uint8_t Des::pc1[2][28]={
	{
		57,49,41,33,25,17,9,1,
		58,50,42,34,26,18,10,2,
		59,51,43,35,27,19,11,3,
		60,52,44,36},
	{
		63,55,47,39,31,23,15,7,
		62,54,46,38,30,22,14,6,
		61,53,45,37,29,21,13,5,
		28,20,12,4}
};
//循环左移表
const uint8_t Des::ls[16]={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
//置换选择表
const uint8_t Des::pc2[48]={
	14,17,11,24,1,5,
	3,28,15,6,21,10,
	23,19,12,4,26,8,
	16,7,27,20,13,2,
	41,52,31,37,47,55,
	30,40,51,45,33,48,
	44,49,39,56,34,53,
	46,42,50,36,29,32
};
//初始置换表
const uint8_t Des::ip[64]={
	58,50,42,34,26,18,10,2,
	60,52,44,36,28,20,12,4,
	62,54,46,38,30,22,14,6,
	64,56,48,40,32,24,16,8,
	57,49,41,33,25,17,9,1,
	59,51,43,35,27,19,11,3,
	61,53,45,37,29,21,13,5,
	63,55,47,39,31,23,15,7
};
//扩展变换表
const uint8_t Des::e[48]={
	32,1,2,3,4,5,
	4,5,6,7,8,9,
	8,9,10,11,12,13,
	12,13,14,15,16,17,
	16,17,18,19,20,21,
	20,21,22,23,24,25,
	24,25,26,27,28,29,
	28,29,30,31,32,1
};

//压缩变换表
const uint8_t Des::s[8][64]={
	//s1
	{
		14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,
		0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8,
		4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0,
		15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13
	},
	//s2
	{
		15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10,
		3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5,
		0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15,
		13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9
	},
	//s3
	{
		10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8,
		13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1,
		13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7,
		1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12
	},
	//s4
	{
		7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15,
		13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9,
		10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4,
		3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14
	},
	//s5
	{
		2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9,
		14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6,
		4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14,
		11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3
	},
	//s6
	{
		12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11,
		10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8,
		9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,
		4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13
	},
	//s7
	{
		4,11,2,14,15,0,8,13,3,12,9,7,5,10,3,1,
		13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6,
		1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2,
		6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12
	},
	//s8
	{
		13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7,
		1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2,
		7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8,
		2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11
	}
};
//置换变换表
const uint8_t Des::p[32]={
	16,7,20,21,29,12,28,17,
	1,15,23,26,5,18,31,10,
	2,8,24,14,32,27,3,9,
	19,13,30,6,22,11,4,25
};
//逆初始置换表
const uint8_t Des::iip[64]={
	40,8,48,16,56,24,64,32,
	39,7,47,15,55,23,63,31,
	38,6,46,14,54,22,62,30,
	37,5,45,13,53,21,61,29,
	36,4,44,12,52,20,60,28,
	35,3,43,11,51,19,59,27,
	34,2,42,10,50,18,58,26,
	33,1,41,9,49,17,57,25
};

//生成初始密钥
uint64_t Des::generateKey(void) const{
	srand(time(NULL));
	uint64_t K0=0;
	int checksum=0;
	for(int i=0;i<64;i++){
		if((i+1)%8){//非校验位
			if(rand()&1){//产生随机数按位与1（随机数是奇数时条件成立）
				K0|=bm64[i];	//如果随机产生的是奇数K0中对应比特位为1	，
				checksum=1;	//反之为0
			}
		}
		else {//校验位
			if(!checksum&1){
				K0|=bm64[i];
			}
			checksum=0;
		}
	}
	return K0;
}
//加密
//mbuf 明文缓冲区 mlen 明文长度
//cbuf 密文缓冲区 clen 密文长度
int Des::encrypt(uint64_t key,const void *mbuf,size_t mlen,void *cbuf,size_t* clen)const{
	//检查密文缓冲区长度
	size_t nlen = (mlen/8+(mlen%8!=0))*8;
	if(*clen<nlen){
		*clen=nlen ;
		return -1;
	}
	*clen = nlen ;
	//校验初始密钥
	if(verifykey(key)==-1){
		return -2;
	} 
	//生成子密钥
	uint64_t roundKeys[16];
	generateRoundKeys(key,roundKeys);
	const uint64_t *M=(const uint64_t *)mbuf;
	uint64_t *C=(uint64_t *)cbuf;
	while(mlen){
		if(mlen>=8){
			*C=M2C(roundKeys,*M);
		}
		else{//最后一个分组长度不足8，补齐
			//x x x x x 
			//x x x x x 0 0 3 
			//
			uint8_t tail[8]={0};
			memcpy(tail,M,mlen);
			tail[7]=8-mlen;
			//加密分组
			*C=M2C(roundKeys,*(uint64_t*)tail);
			break;
		}
		++C;
		++M;
		mlen-=8;
	}
	return 0;
}
//解密
int Des::decrypt(uint64_t key,const void *cbuf,size_t clen,void *mbuf,size_t *mlen)const {
	//检查明文缓冲区长度
	if(*mlen < clen ){
		*mlen = clen ;
		return -1;
	}
	*mlen = clen ;
	//校验初始密钥
	if(verifykey(key)==-1){
		return -2;
	}
	//生成子密钥
	uint64_t roundKeys[16];
	generateRoundKeys(key,roundKeys);
	const uint64_t * C = (const uint64_t *)cbuf;
	uint64_t *M = (uint64_t *)mbuf;
	while(clen){
		//解密分组
		*M = C2M(roundKeys,*C);

		if(clen==8){//刚刚解密的是最后一个分组
			uint8_t tail[8];
			memcpy(tail,M,8);
			if(tail[7]<8){//可能存在尾块补齐
				size_t i;
				for(i=8-tail[7];i<7&&!tail[i];i++);
				if(i == 7){//存在尾块补齐
					*mlen -= tail[7];//减去补齐部分的长度
				}
			}
		}
		C++;
		M++;
		clen-=8;
	}
	return 0;
}
//校验初始密钥
int Des::verifykey(uint64_t K0)const{
	int checksum = 0;
	for(int i=0;i<64;i++){
		if(K0&bm64[i]){
			checksum++;
		}
		if((i+1)%8==0){
			if(!checksum&1){//校验位
				return -1;//奇校验
			}
			checksum=0;
		}
	}
	return 0;
}

//置换选择PC1
void Des::PC1(uint64_t K0,uint32_t *C,uint32_t *D)const{
	*C=*D=0;
	for(int i=0;i<28;i++){
		if(K0&bm64[pc1[0][i]-1]){
			*C|=bm32[i];
		}
		if(K0&bm64[pc1[1][i]-1]){
			*D|=bm32[i];
		}
	}
}
//循环左移
void Des::LS(int iKey,uint32_t *C,uint32_t *D)const{
	uint8_t N=ls[iKey];
	//左端移出部分掩码
	uint32_t lm=0;
	for(int i=0;i<N;i++){
		lm |= bm32[i];
	}
	*C = *C << N | (*C & lm) >> (28-N);
	*D = *D << N | (*D & lm) >> (28-N);
}

//置换选择 PC2
uint64_t Des::PC2(uint32_t C,uint32_t D)const{
	uint64_t CD=C;
	CD = (CD<<28|D)<<4;
	uint64_t K=0;
	for(int i=0;i<48;i++){
		if(CD & bm64[pc2[i]-1]){
			K|=bm64[i];
		}
	}
	return K; 
}
//生成子密钥
void Des::generateRoundKeys(uint64_t K0,uint64_t *roundKeys)const{
	uint32_t C,D;
	PC1(K0,&C,&D);
	for(int iKey=0;iKey<16;iKey++){
		LS(iKey,&C,&D);
		roundKeys[iKey]=PC2(C,D);
	}
}
//选择扩展运算
uint64_t Des::E(uint32_t R)const{
	uint64_t _R=0;
	for(int i=0;i<48;i++){
		if(R&bm32[e[i]-1]){
			_R|=bm64[i];
		}
	}
	return _R;
}
//密钥加运算
uint64_t Des::X(uint64_t R,uint64_t K)const{
	return R^K;
}
//选择压缩运算
uint32_t Des::S(uint64_t R)const{
	uint64_t gm=63;//组掩码：111111
	uint32_t _R=0;
	for(int i=0;i<8;i++){
		_R |= s[i][(R & gm << (64-(i+1) * 6))>> (64-(i+1)*6)]<<(32-(i+1)*4);
	}
	return _R;
}
//置换运算
uint32_t Des::P(uint32_t R)const{
	uint32_t _R=0;
	for(int i=0;i<32;i++){
		if(R&bm32[p[i]-1]){
			_R|=bm32[i];
		}
	}
	return _R;
}
//加密变换
uint32_t Des::F(uint32_t R,uint64_t K)const{
	return P(S(X(E(R),K)));
}
//初始置换
void Des::IP(uint64_t M,uint32_t *L,uint32_t *R)const{
	uint64_t _M=0;
	for(int i=0;i<64;i++){
		if(M&bm64[ip[i]-1]){
			_M |= bm64[i];
		}
	}
	*L=_M>>32;
	*R=_M;
}
//16轮迭代
void Des::R16(const uint64_t *roundKeys,uint32_t *L,uint32_t *R)const{
	for(int i=0;i<16;i++){
		if(i<15){//前15轮迭代
			uint32_t _L=*L;
			*L=*R;
			*R=_L^F(*R,roundKeys[i]);
		}
		else{//最后一轮迭代
			*L=*L^F(*R,roundKeys[i]);
		}
	}
}
//逆初始置换
uint64_t Des::IIP(uint32_t L,uint32_t R)const{
	uint64_t LR=L;
	LR=LR<<32|R;
	uint64_t C=0;
	for(int i=0;i<64;i++){
		if(LR&bm64[iip[i]-1]){
			C|=bm64[i];
		}
	}
	return C;
}
//加密分组
uint64_t Des::M2C(const uint64_t *roundKeys,uint64_t M)const{
	uint32_t L,R;
	//初始置换
	IP(M,&L,&R);
	//16轮迭代
	R16(roundKeys,&L,&R);
	//逆初始置换
	return IIP(L,R);
}
//解密分组
uint64_t Des::C2M(const uint64_t *roundKeys,uint64_t C)const{
	//16个子密钥逆序
	uint64_t inverseKeys[16];
	for(int i=0;i<16;i++){
		inverseKeys[i]=roundKeys[15-i];
	}
	uint32_t L,R;
	//初始置换
	IP(C,&L,&R);
	//16轮迭代
	R16(inverseKeys,&L,&R);
	//逆初始置换
	return IIP(L,R);
}




